In 1974, two hardy divers descended into the pit in an attempt to find the water's origin, but died while attempting to navigate its narrow passages. More than 20 years later, another diver went down into the well and met the same sorry fate. In October 2019, professional diver Pierre-Éric Deseigne was hired by the town to explore the spring, filming as he went. He managed to descend some 1,214 feet (370m) underwater, further than anyone had ever been before. But, while his footage gave some indication of what it’s like down there, he still couldn’t locate the spring’s source.
These are Europe's most mysterious places